Improved prognosis for asymptomatic carotid stenosis with prophylactic carotid endarterectomy

Carotid Endarterectomy: The Gold Standard

Carotid endarterectomy has been firmly established as the gold standard of therapy for symptomatic and asymptomatic patients with severe carotid stenosis, provided surgical complication rates are within prescribed limits. The procedure-related risk of stroke/death should be < 3% in asymptomatic patients and < 6% in symptomatic patients. New investigational therapies such as balloon angioplasty and stenting for carotid stenosis should be evaluated against the same standard.

Cost Analysis of Carotid Endarterectomy: Is Age a Factor?

Carotid endarterectomy (CEA) has been demonstrated to be safe and effective in elderly patients. Our aim was to analyze and compare outcome and cost of CEA in both elderly and younger patient groups. A total of 125 consecutive patients who underwent CEA were examined retrospectively and grouped according to age (<80 years old, n = 95; and >or=80 years old, n = 30). The actual total costs and itemized costs were analyzed, and diagnosis-related group (DRG) code payor mix were identified. Patient demographics and risk factors were similar except for a greater incidence of coronary artery disease (CAD) in the >or=80 group than in these <80 (43.3% vs. 21.1%, p < 0.05). Patients had similar minor complication rates; however, the >or=80 group had higher perioperative major complications (16.7% vs. 1.1%, p < 0.01). There were no deaths and there was one perioperative stroke, which occurred in the <80 group. Mean length of stay (LOS), intensive care unit (ICU) LOS, and ICU admissions were greater in the >or=80 group. Cost figures were normalized to a base value of 10 US dollars to maintain proprietary data. Actual total costs of CEA were 131.50 US dollars for the >or=80 group and $100 for the <80 group (p < 0.001). Significant cost differences were found in ICU room costs, and costs for clinical laboratory, radiology imaging, other specialty consults, operating room, and ancillary services in the >or=80 group compared with the <80 group. These results show that the cost of CEA in the elderly is significantly greater than that for younger patients. This difference can be attributed to a greater number of major complications in the more elderly group, who require increased ICU stay, and thus require more clinical laboratory, radiology imaging, and specialty consult service resources. Consideration should be given for a DRG modifier code to increase hospital reimbursement for increased associated costs in elderly patients undergoing CEA.

Changing characteristics of carotid endarterectomy

We have noted significant differences in terms of our preoperative work-up, length of stay, morbidity, and mortality of patients undergoing carotid endarterectomy (CEA) from findings reported in large published randomized clinical trials. To further investigate these differences, we have reviewed our recent experience. CEA has proved to be the most effective approach to avert stokes caused by significant atherosclerotic disease of the carotid bifurcation. Between January 1, 1996 and December 31, 1998, 552 patients underwent CEA at our institution. Forty percent were performed in symptomatic patients with stenotic lesions > 60% in diameter by duplex ultrasonography. The remainder were performed for asymptomatic lesions > 60% in diameter. No patient underwent contrast angiography. Fifty-two percent of the patients were males. The mean age was 74 +/- 8 years old. General anesthesia was used in 97% of the cases and regional block, in 3%. All patients underwent routine postoperative measurement of serum creatinine phosphokinase (CPK) isoenzymes. Patients were discharged when deemed clinically stable. The patients' follow-up visits at 1 week and at 3-5 months after the procedure (mean, 3.4 months) included a neurological exam and duplex exam. Patient results suggest that CEAs can be performed in the modern era without contrast arteriography. Most patients can be discharged on the first postoperative day. In addition, previously acceptable rates of postoperative morbidity and mortality should perhaps be revised to meet current standards. Contrary to the previous concept that most postoperative strokes are due to embolic phenomena, hyperperfusion syndrome played an increasingly important role in this review.

Carotid Endarterectomy for Severe Asymptomatic Carotid Stenosis: A Perioperative Experience at a Community Hospital

The purpose of this study was to evaluate the safety and feasibility of carotid endarterectomy (CEA) for severe asymptomatic carotid stenosis in a community setting with direct surgical resident participation. The medical records of all patients who had undergone CEA for severe asymptomatic carotid stenosis between 1989 and 1997 were retrospectively reviewed to ascertain perioperative morbidity and mortality. One hundred forty-seven CEAs were performed on 131 patients over the 8-year interval. Perioperative stroke and death rate was 0 per cent. However, one patient had a postoperative transient ischemic attack, and one patient had vocal cord dysfunction due to vagus nerve injury (1.3%). Three other patients had perioperative complications not directly related to CEA (2.1%). Therefore the total perioperative complication rate of (3.4%) compares favorably with results reported by several large tertiary referral centers. CEA for severe asymptomatic carotid stenosis can be safely performed in a community hospital setting with direct surgical resident participation.

Cost-effectiveness of carotid endarterectomy in asymptomatic patients

PURPOSE

The purpose of this study was to determine the cost-effectiveness of carotid endarterectomy for treating asymptomatic patients with > or = 60% internal carotid stenosis, based on outcomes reported in the Asymptomatic Carotid Atherosclerosis Study (ACAS).

METHODS

A cost-effectiveness analysis was performed using a Markov decision model in which the probabilities for base-case analysis (average age, 67 years; 66% male; perioperative stroke plus death rate, 2.3%; ipsilateral stroke rate during medical management, 2.3% per year) were based on ACAS. The model assumed that patients who had TIAs or minor strokes during medical management crossed over to surgical treatment, and used the NASCET data to model the outcome of these now-symptomatic patients. Average cost of surgery ($8500), major stroke ($34,000 plus $18,000 per year), and other costs were based on local cost determinations plus a review of the published literature. Cost-effectiveness was calculated as the incremental cost of surgery per quality-adjusted life year (QALY) saved when compared with medical treatment, discounting at 5% per year. Sensitivity analysis was performed to determine the impact of key variables on cost-effectiveness.

RESULTS

In the base-case analysis, surgical treatment improved quality-adjusted life expectancy from 7.87 to 8.12 QALYs, at an incremental lifetime cost of $2041. This yielded an incremental cost-effectiveness ratio of $8,000 per QALY saved by surgical compared with medical treatment. The high cost of care after major stroke during medical management largely offset the initial cost of endarterectomy in the surgical group. Furthermore, 26% of medically managed patients eventually underwent endarterectomy because of symptom development, which also decreased the cost differential. Sensitivity analysis demonstrated that the relative cost of surgical treatment increased substantially with increasing age, increasing perioperative stroke rate, and decreasing stroke rate during medical management.

CONCLUSION

For the typical asymptomatic patient in ACAS with > or = 60% carotid stenosis, our results indicate that carotid endarterectomy is cost-effective when compared with other commonly accepted health care practices. Surgery does not appear cost-effective in very elderly patients, in settings where the operative stroke risk is high, or in patients with very low stroke risk without surgery.

The influence of routine completion arteriography on outcome following carotid endarterectomy

The necessity for routine completion arteriography (RCA) following carotid endarterectomy (CEA) is controversial, with the reported yield of clinically significant findings varying from 3% to 16%. In order to determine the utility of RCA, we reviewed completion studies in 154 consecutive CEAs, defined the frequency and characteristics of arteriographic defects, and correlated RCA defects with early outcome (internal carotid artery [ICA] occlusion, stroke) and late restenosis. All intraoperative RCAs were reviewed by two blinded observers and categorized into three subsets: Group A (n = 69) normal; Group B (n = 29), abnormal, severe defects; Group C (n = 56), abnormal, mild-moderate defect. RCA detected 32 defects in Group B: 10 internal carotid (ICA), seven endpoint flaps, two kinks, one dissection; 16 external carotid (ECA), 10 severe endpoint defects and six total occlusion; six common carotid (CCA), five irregular proximal shelfs, one web. Thirty of 32 defects were successfully repaired as confirmed by normal repeat RCA studies; one ECA defect was not repaired and the ICA dissection was irreparable. In Group C, 67 mild-moderate defects were identified, but not corrected. These included < 30% stenosis in the ICA (12), ECA (18), CCA (24), and vein patch corrugation or irregularity (13). For the entire series the postoperative ICA occlusion rate was 2% (3/154), stroke rate 2.6% (4/154), and a subsequent > 50% restenosis rate of 7% (11/154). The yield from routine carotid completion arteriograms was significant, with 19% of studies identifying a severe defect that required repair. Although the difference in stroke rates and restenosis between the different groups did not reach statistical significance, patients with normal intraoperative arteriograms initially or after correction of a significant RCA defect had no early carotid occlusion (p = 0.05, Fisher's exact test) compared to patients with residual RCA defects. All early carotid occlusions occurred in patients with unrepaired defects. We conclude that RCA is an important method of quality control after CEA and exerts a subtle, but real, reduction in postoperative complications.

Cost reduction by combined carotid endarterectomy and coronary artery bypass grafting

A significant cost reduction is likely if patients who require coronary artery bypass grafting with significant carotid stenosis have simultaneous carotid endarterectomy and bypass grafting, provided risk is not increased. To investigate this issue, we retrospectively identified cases from February 1977 to May 1994 with first-time isolated carotid endarterectomy, coronary bypass, or combined procedures. In the isolated carotid endarterectomy population, median age was 69 years and 58% (85/146) were male, as compared with 68 years and 68% (68/100) male in the combined group; median age of the coronary bypass cohort was 65 years and 76% (381/500) male. A significantly higher percentage of patients in the coronary bypass versus combined group were in New York Heart Association functional class IV. In the combined group there was a significantly higher incidence of older age, diabetes, hypertension, hyperlipidemia, renal failure, and congestive heart failure. There was no difference among the three groups with respect to hospital mortality (0%, 3.4%, and 4.0%, respectively) and permanent stroke (0.7%, 1.2%, and 0%, respectively). Hospital costs were $4,896, $10,959 and $11,089, respectively, with a savings of $4,766 (30%), and Medicare hospital reimbursement was $8,575, $23,071, and $23,071, respectively, with a savings of $10,077 (25.3%). Thus, in appropriate patients, a combined procedure is cost effective, eliminating a second surgical procedure and the cost of the postoperative stay (3.7 +/- 2.4 days) associated with isolated carotid endarterectomy. Risk of permanent stroke or death is not increased.

Carotid endarterectomy: the gold standard

Carotid endarterectomy has been firmly established as the gold standard of therapy for symptomatic and asymptomatic patients with severe carotid stenosis, provided surgical complication rates are within prescribed limits. The procedure-related risk of stroke/death should be < 3% in asymptomatic patients and < 6% in symptomatic patients. New investigational therapies such as balloon angioplasty and stenting for carotid stenosis should be evaluated against the same standard.

The natural history of moderate (50% to 79%) internal carotid artery stenosis in symptomatic, nonhemispheric, and asymptomatic patients

PURPOSE

This study was undertaken to determine the incidence of disease progression of moderate (50% to 79%) internal carotid artery stenosis in patients with symptoms, patients with nonhemispheric symptoms, and symptom-free patients and to define the risk of development of new neurologic events in each group.

METHODS

Over a 6-year period, 272 patients with moderate internal carotid artery stenoses were monitored for a mean of 44 months with color-flow duplex scanning (CFS). At the time of the initial scan, 142 patients were symptom free, 87 had experienced transient ischemic attacks, amaurosis fugax, or mild strokes, and 43 had ill-defined nonhemispheric symptoms. The average number of follow-up scans was 2.4 per patient (range 1 to 11).

RESULTS

During follow-up, 23 (26%) of the patients with symptoms, 17 (40%) of the patients with nonhemispheric symptoms, and 30 (21%) of the symptom-free patients had development of additional neurologic symptoms. Life-table comparison of ipsilateral ischemic events showed a significantly (p = 0.03) higher cumulative rate in the symptomatic group (20%) than in the asymptomatic group (7%) at 2 years. Mean annual stroke rates were 6% and 2% in patients in the symptomatic and asymptomatic groups, respectively. None of the patients in the nonhemispheric group had a stroke within 4 years of the initial study. Disease progression occurred in 16% of the patients. In the asymptomatic group, ipsilateral stroke occurred more frequently (p = 0.0001) in patients with disease progression (25%) than in patients with stable lesions (1%). CFS detected disease progression in 19 (79%) of 24 patients before the artery occluded or stroke occurred. In patients with symptoms, stroke was more frequent (p = 0.02) in patients with six or more risk factors (29%) than in those with five or fewer risk factors (7%).

CONCLUSION

Although the risk of stroke is less in patients with moderate stenosis than it is in patients with severely stenotic lesions, symptom-free patients with advancing disease and patients with symptoms and multiple risk factors are at increased risk for development of neurologic events. These findings support the use of CFS to monitor patients with carotid artery disease and suggest that a more aggressive surgical approach may be indicated in selected patients with moderate carotid artery stenosis.

Outcome after carotid endarterectomy for asymptomatic carotid stenosis

OBJECTIVE

To compare the long-term outcome in patients with asymptomatic carotid stenosis (ACS) among those treated with carotid endarterectomy (CE) or medical therapy.

BACKGROUND

Until randomized trials are completed, treatment of ACS will depend on identification of subgroups likely to benefit from CE.

METHODS

A retrospective cohort study was done on 215 patients with ACS: 107 underwent CE, and 108 were treated medically (MED). A neurologist reviewed medical records and performed a telephone interview to detect outcome (stroke and death). Mean follow-up was 3.8 years; only 4% were lost to follow-up.

RESULTS

Among CE patients, there was a 4.7% risk of postoperative ipsilateral stroke within 30 days. Four of five postoperative strokes occurred among patients with prior contralateral symptoms. There was no significant difference between CE and MED in the cumulative life-table 5-year risk of ipsilateral stroke, any stroke, or survival free of any stroke. Among diabetics, however, there were no ipsilateral strokes at 5 years after CE compared to 20% in MED (p = 0.03). Excluding postoperative complications, the 5-year risk of ipsilateral stroke was reduced among CE patients who "ever smoked" (CE 1%, MED 8%, p = 0.03) and the 5-year risk of any stroke was reduced among CE patients who had no prior myocardial infarction (CE 6%, MED 16%, p = 0.02). Among those with prior contralateral carotid territory symptoms, the 5-year risk of any stroke was worse in the MED patients (CE 5% MED 32%, p = 0.004). Among CE patients, a Cox proportional hazards model determined that the independent predictors of worse long-term outcome were: a history of myocardial infarction; admission systolic blood pressure greater than 160 mm Hg; and age greater than 65.

CONCLUSION

The approach to patients with ACS will await completion of large, randomized clinical trials, now in progress. Even if these studies are negative, there may remain specific subgroups of patients who show clear benefit from carotid endarterectomy.

Immediate and long-term results of carotid endarterectomy for asymptomatic high-grade stenosis

We examined the operative risks and long-term results of carotid endarterectomy for asymptomatic patients in terms of stroke, death, and recurrent stenosis. The results of a nonrandomized study with a follow-up of 1 to 104 months (mean 46 months) is reported. A tertiary referral center served as the setting for this report. One hundred consecutive patients with severe but asymptomatic carotid artery stenosis out of a total of 514 patients undergoing carotid endarterectomy were entered into this study. The severity of carotid disease was determined by duplex scanning and confirmed arteriographically. No patients were lost to follow-up after surgery. Eighty-nine operations (77%) were done under cervical block anesthesia and all arteries were closed with saphenous vein patches. Life-table analysis showed that the stroke-free rate at 5 years was 96.3% with an ipsilateral stroke-free rate of 98.2%. The 5-year overall survival rate was 78.2% with a stroke-free survival rate of 75%. Carotid endarterectomy can be performed safely for asymptomatic patients believed to be at risk for stroke. The potential for early death due to myocardial disease, late stroke, and recurrent stenosis do not justify advising patients against undergoing prophylactic carotid endarterectomy for asymptomatic high-grade stenosis.

Brain blood flow restoration 'rescues' chronically damaged rat CA1 neurons

Middle aged rats (13 months) were subjected to chronic cerebrovascular insufficiency (CVI) for 9 weeks using a 3-vessel occlusion technique. This CVI injury targets CA1 neuron damage selectively. Three groups of rats had their cerebral blood flow restored after 1, 2 or 3 weeks following CVI by removal of their carotid artery occluders. Another rat group did not undergo deocclusion for the 9 week observation period. Rats were tested for memory acquisition and retention 6 and 9 weeks after CVI using a modified water maze test. At the end of the 9 weeks, cerebral blood flow was measured in the fronto-parietal cortex and rats were killed by fixation-perfusion. Hippocampal morphometry was done to assess the % of damaged CA1 neurons and the density of GFAP-positive hyperplasia and hypertrophy. Results show that restoration of cerebral blood flow 1 and 2 weeks after CVI but not after 3 weeks of CVI, reversed a significant increase in reactive astrocytosis and prevented memory impairment in these deoccluded rats when compared to the non-deoccluded group. It appears from these results that 'neuronal rescue' of CA1 neurons is possible when cerebral blood flow is restored in rats subjected to chronic CVI during a 2 week (but not 3 week) 'window of opportunity'. This chronic brain ischemia model may be useful in screening potential therapy in patients with dementia where spatial memory impairment and hippocampal damage may be manifested.